Where do I change the name of a Dimension/Measure and change the fields aliases?

Resolution:

Right click on the Dimension/Measure you want to Alter and select 'Rename...' to change the Name of the field. Select 'Field Properties' > 'Aliases...' to map database values to values you want to use in Tableau.

I have also attached a png specifically showing where the menu items are.

I really appreciate the reply. If you look at my screenshot, Field Properties -> Aliases doesn't exist in my menu structure.

Is it something to do with the format / location / structure of my data perhaps? I have a new symbol next to my dimension name, not the "abc" you have. I'm starting to think that because I'm connecting to a cube (instead of a flat file), many, many features disappear... ?